Method for fabricating a magnetoresistive (MR) read head

ABSTRACT

A magnetoresistive (MR) read head is disclosed including a shield layer with a recessed portion and a protruding portion defined by the recessed portion. Also included is an MR sensor located in vertical alignment with the protruding portion of the shield layer. Further provided is at least one gap layer situated above and below the MR sensor. At least one of such gap layers is positioned in the recessed portion of the shield layer. By this design, a combined thickness of the gap layers is thinner adjacent to the MR sensor and the protruding portion of the shield layer, while being thicker adjacent to the recessed portion of the shield layer. As such, optimum insulation is provided while maintaining planar gap layer surfaces to avoid the detrimental ramifications of reflective notching and the swing curve effect.

The present application is a divisional of U.S. application Ser. No.09/875,405 which was filed on Jun. 5, 2001, now U.S. Pat. No. 6,628,484which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to magnetoresistive read sensors forreading signals recorded in a magnetic medium, and more particularly,this invention relates to improving gap layers of a magnetoresistiveread sensor to optimize operating characteristics.

BACKGROUND OF THE INVENTION

Computer systems generally utilize auxiliary memory storage deviceshaving media on which data can be written and from which data can beread for later use. A direct access storage device (disk drive)incorporating rotating magnetic disks is commonly used for storing datain magnetic form on the disk surfaces. Data is recorded on concentric,radially spaced tracks on the disk surfaces. Magnetic heads includingread sensors are then used to read data from the tracks on the disksurfaces.

In high capacity disk drives, magnetoresistive read sensors, commonlyreferred to as MR heads, are the prevailing read sensors because oftheir capability to read data from a surface of a disk at greater lineardensities than thin film inductive heads. An MR sensor detects amagnetic field through the change in the resistance of its MR sensinglayer (also referred to as an “MR sensor”) as a function of the strengthand direction of the magnetic flux being sensed by the MR layer.

FIG. 1 illustrates a cross-sectional view of an MR head, in accordancewith the prior art. As shown, an MR read head includes an MR sensorwhich is sandwiched between first and second gap layers G1 and G2 whichare in turn sandwiched between first and second shield layers S1 and S2.Lead layers are sandwiched between the first and second gap layers forproviding a sense current to the MR sensor. Magnetic fields from amagnetic disk change the resistance of the sensor proportional to thestrength of the fields. The change in resistance changes the potentialacross the MR sensor which is processed by channel circuitry as areadback signal.

An MR read head is typically mounted to a slider which, in turn, isattached to a suspension and actuator of a magnetic disk drive. Theslider and edges of the MR sensor and other layers of the read head forman air bearing surface (ABS). When a magnetic disk is rotated by thedrive, the slider and one or more heads are supported against the diskby a cushion of air (an “air bearing”) between the disk and the ABS. Theair bearing is generated by the rotating disk. The read head then readsmagnetic flux signals from the rotating disk.

There are two critical dimensions of the MR head, namely the trackwidthand resolution of the MR head. The capability of the MR head to readdata recorded at high areal densities is determined by its trackwidthand its resolution.

The trackwidth of the MR read head is the length of the active orsensing region for the MR sensor and is typically defined by thephotolithography and subtractive or additive processing. The trackwidthis defined by the recess generated by the photoresist PR used during aphotolithography process.

Resolution, on the other hand, is determined by the gap of the read headwhich is the distance between the first and second shield layers at theABS. Accordingly, this distance is the total of the thicknesses of theMR sensor and the first and second gap layers G1 and G2. When the firstand second gap layers G1 and G2, which separate the MR sensor from thefirst and second shield layers S1 and S2, become thinner, the linearresolution of read head becomes higher. A serious limitation on thethinness of the gap layers of the read head is the potential forelectrical shorting between the lead layers and the first and secondshield layers. The thinner a gap layer, the more likely it is to haveone or more pinholes which expose a lead layer to a shield layer.Pinholes can significantly reduce the yield of a production run of MRread heads.

It is important to note that the only place where the gap layers have tobe thin is in an MR region where the MR sensor is located. The gaplayers can be thicker between the lead layers and the first and secondshield layers. Accordingly, it is desirable if each gap layer could bethin in the MR region to provide high linear resolution and thickoutside of the MR region to provide good insulation between the leadlayers and the shield layers.

The MR read head of FIG. 1 accomplishes this using a two step process ofdepositing first gap layers before the MR sensor is deposited and a twostep process of depositing second gap layers after the MR sensor isdeposited. In the present device, a very thin first gap layer G1 isdeposited on the first shield layer S1. An MR region is then masked anda first gap pre-fill layer G1P, which may be thicker than G1, isdeposited. The mask is removed, leaving the first gap pre-fill layer G1Peverywhere except in the MR region. Lead layers L1 and L2 and an MRsensor are then formed.

Next, a very thin second gap layer G2 is deposited. The MR region isthen masked and a second gap pre-fill layer G2P is deposited. Afterlifting off the mask, the G2P layer is located everywhere except in theMR region. The result is that very thin G1 and G2 layers are in the MRregion at the bottom and top of the MR sensor to provide the MR headwith a high linear resolution, the G1 and G1P layers are located betweenthe leads and the first shield layer S1 to prevent shorting between thelead layers and the first shield layer S1, and the G2 and G2P layers arelocated between the lead layers and the second shield layer S2 toprevent shorting between the lead layers and the second shield layer S2.

As such, the present device is capable of providing a read head whichhas a very thin gap layer at the MR region, and yet will prevent shortsbetween lead layers and the first and second shield layers.

Despite this, the MR read head of FIG. 1 includes gap layers G1, G1P,G2, and G2P which afford many non-planar surfaces in the form of bevelededges circumnavigating the MR sensor. Such non-planar surface must, inturn, be subjected to photoresist layers during processing. Due toinherent limitations of photolithography, two problems result whichcompromise control of the critical trackwidth and resolution dimensions.

First, the beveled edges cause reflective notching due to lightscattering. See arrows in FIG. 1. Secondly, the non-planar surfacescause non-uniform photoresist coverage during processing which, in turn,invokes the well known “swing curve” effect. FIG. 2 illustrates themanner in which the critical dimensions (trackwidth and resolution) varyas a function of photoresist thickness, in accordance with the swingcurve effect. As is well known, the constructive and destructiveinterference of reflected light within the photoresist film causes theswing curve effect.

Prior art devices have attempted to overcome the foregoing disadvantagesthrough the addition of antireflective layers and planarization.Unfortunately, antireflective layers are only partially effective andintroduce complications associated with their removal.

There is therefore a need for an MR read head with an improved gap layerwhich utilizes planar surfaces to avoid adversely affecting the MRregion, while providing a thin gap layer adjacent to the MR region and athick gap layer between lead layers and the first and second shieldlayers.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to disclose a magnetoresistive(MR) read head with an improved gap layer which does not adverselyaffect the MR region.

It is another object of the present invention to disclose an MR readhead which has a very thin gap layer adjacent to the MR region.

It is still another object of the present invention to disclose an MRread head which has a very thick gap layer between lead layers and thefirst and second shield layers of the MR read head.

It is still yet another object of the present invention to disclose anMR read head which has gap layers that are planar to avoid the negativeramifications of reflective notching and the swing effect.

These and other objects and advantages are attained in accordance withthe principles of the present invention by disclosing an MR read headincluding a shield layer with a recessed portion and a protrudingportion defined by the recessed portion. Also included is an MR sensorlocated in vertical alignment with the protruding portion of the shieldlayer. Further provided is at least one gap layer situated above andbelow the MR sensor. At least one of such gap layers is positioned inthe recessed portion of the shield layer.

In one embodiment of the present invention, the gap layers may include afirst gap layer located on top of the recessed portion of the shieldlayer. Such first gap layer may include an upper surface substantiallylevel with an upper surface of the protruding portion of the shieldlayer. As an option, the recessed portion of the shield layer may beformed by an etching process.

The gap layers may further include a second gap layer located on top ofthe first gap layer and the protruding portion of the shield layer. TheMR sensor may be located on top of the second gap layer. As a result ofthe aforementioned underlying structure, an upper surface of such secondgap layer may be planar to avoid the negative ramifications ofreflective notching and the swing effect.

In addition to the first and second gap layers, a third gap layer may belocated on top of the MR sensor.

To this end, a combined thickness of the first gap layer, second gaplayer, and third gap layer is thinner adjacent to the MR sensor and theprotruding portion of the shield layer than the recessed portion of theshield layer for insulation purposes.

In yet another embodiment, a method is provided for fabricating the MRread head. Initially, a shield layer is deposited. Thereafter, arecessed portion is etched in an upper surface of the shield layer. Suchrecessed portion of the shield layer defines a protruding portion of theshield layer. A first gap layer is deposited on top of the recessedportion of the shield layer, and a second gap layer is deposited on topof the first gap layer and the protruding portion of the shield layer.Next, an MR sensor is positioned on top of the second gap layer invertical alignment with the protruding portion of the shield layer.First and second lead layers are subsequently positioned on top of thesecond gap layer. The first and second lead layers are positioned suchthat they are connected to the MR sensor. A third gap layer is thendeposited on top of the second gap layer, the MR sensor, and the firstand second lead layers.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, as well as the preferred mode of use, reference should bemade to the following detailed description read in conjunction with theaccompanying drawings.

FIG. 1 illustrates a cross-sectional view of a (magnetoresistive) MRhead, in accordance with the prior art.

FIG. 2 illustrates the manner in which the critical dimensions vary as afunction of photoresist thickness, in accordance with the swing curveeffect.

FIG. 3 is a perspective drawing of a magnetic recording disk drivesystem.

FIG. 4 illustrates an MR read head constructed in accordance with oneembodiment of the present invention.

FIG. 5 illustrates a plan cross-sectional view of the MR read head takenalong line 5—5 shown in FIG. 4.

FIG. 6 illustrates a method for fabricating the MR read head of FIGS. 4and 5.

FIGS. 7A–7I illustrate the MR read head during the various stages offabrication in accordance with FIG. 6.

BEST MODE FOR CARRYING OUT THE INVENTION

The following description is the best embodiment presently contemplatedfor carrying out the present invention. This description is made for thepurpose of illustrating the general principles of the present inventionand is not meant to limit the inventive concepts claimed herein.

Referring now to FIG. 3, there is shown a disk drive 300 embodying thepresent invention. As shown in FIG. 3, at least one rotatable magneticdisk 312 is supported on a spindle 314 and rotated by a disk drive motor318. The magnetic recording media on each disk is in the form of anannular pattern of concentric data tracks (not shown) on disk 312.

At least one slider 313 is positioned on the disk 312, each slider 313supporting one or more magnetic read/write heads 321 where the head 321incorporates the MR sensor of the present invention. As the disksrotate, slider 313 is moved radially in and out over disk surface 322 sothat heads 321 may access different portions of the disk where desireddata are recorded. Each slider 313 is attached to an actuator arm 319 byway of a suspension 315. The suspension 315 provides a slight springforce which biases slider 313 against the disk surface 322. Eachactuator arm 319 is attached to an actuator 327. The actuator 327 asshown in FIG. 3 may be a voice coil motor (VCM). The VCM comprises acoil movable within a fixed magnetic field, the direction and speed ofthe coil movements being controlled by the motor current signalssupplied by controller 329.

During operation of the disk storage system, the rotation of disk 312generates an air bearing between slider 313 and disk surface 322 whichexerts an upward force or lift on the slider. The air bearing thuscounter-balances the slight spring force of suspension 315 and supportsslider 313 off and slightly above the disk surface by a small,substantially constant spacing during normal operation.

The various components of the disk storage system are controlled inoperation by control signals generated by control unit 329, such asaccess control signals and internal clock signals. Typically, controlunit 329 comprises logic control circuits, storage and a microprocessor.The control unit 329 generates control signals to control various systemoperations such as drive motor control signals on line 323 and headposition and seek control signals on line 328. The control signals online 328 provide the desired current profiles to optimally move andposition slider 313 to the desired data track on disk 312. Read andwrite signals are communicated to and from read/write heads 321 by wayof recording channel 325.

The above description of a magnetic disk storage system of the presentinvention, and the accompanying illustration of FIG. 3 are forrepresentation purposes only. It should be apparent that disk storagesystems may contain a large number of disks and actuators, and eachactuator may support a number of sliders.

FIG. 4 illustrates an MR read head 400 constructed in accordance withone embodiment of the present invention. As shown, the MR read head 400includes a shield layer S1 with a recessed portion 402 and a protrudingportion 404 defined by the recessed portion 402. In one embodiment, therecessed portion 402 of the shield layer S1 is formed by any desiredetching process. In particular, ion milling, reactive ion etching, wetetching, etc. may be utilized.

Next provided is a first gap layer G1 located on top of the recessedportion 402 of the shield layer S1. The first gap layer G1 includes anupper surface 405 substantially level with an upper surface 406 of theprotruding portion 404 of the shield layer S1. The first gap layer G1and the remaining gap layers may be constructed utilizing alumina,aluminum oxide, or any other desired insulating material. Moreover, suchgap layers may be deposited utilizing any desired process such assputtering or the like.

As an option, the upper surface 405 of the first gap layer G1 may resideslightly below the upper surface 406 of the protruding portion 404 ofthe shield layer S1. In such embodiment, a chemical-mechanical polishingprocess or the like may be utilized to achieve planarity. It ispreferred that the upper surface 405 of the first gap layer G1 be planarand level with the upper surface 406 of the protruding portion 404 inorder to avoid reflective notching and the swing curve effect.

With continuing reference to FIG. 4, a second gap layer G2 is shown tobe located on top of the first gap layer G1 and the protruding portion404 of the shield layer S1. Similar to the upper surface 405 of thefirst gap layer G1, it is preferred that an upper surface 410 of thesecond gap layer G2 is planar.

Located on top of the second gap layer G2 is an MR sensor that ispositioned in vertical alignment with the protruding portion 404 of theshield layer S1. In one embodiment, the size and shape of the protrudingportion 404 of the shield layer S1 is similar to that of the MR sensor.Preferably, the size of the protruding portion 404 of the shield layerS1 is slightly larger than that of the MR sensor. The MR sensor may beconstructed utilizing Permalloy (nickel iron) or any other desiredmaterial. Moreover, the MR sensor may be deposited utilizing any desiredprocess such as sputtering, vacuum deposition, plating or the like.

Also located on top of the second gap layer G2 are first and second leadlayers which are connected to the MR sensor. The first and second leadlayers may be constructed utilizing copper or any other conductivematerial. Similar to the MR sensor, the first and second lead layers maybe deposited utilizing any desired process such as sputtering, vacuumdeposition, plating or the like.

A third gap layer G3 is located on top of the MR sensor, the first andsecond lead layers, and the second gap layer G2. While not shown, itshould be noted that another shield layer S2 and other layers may bedeposited on top of the third gap layer G3, as is well known to those ofordinary skill. In use, the gap layers provide insulation between thelead layers and the shield layers S1 and S2.

By this design, a combined thickness of the first gap layer G1, secondgap layer G2, and third gap layer G3 is thinner adjacent to the MRsensor and the protruding portion 404 of the shield layer S1 than therecessed portion 402 of the shield layer S1. As such, the lead layersenjoy the increased combined thickness of the gap layers. This isimportant to reduce the chance of a short occurring between the leadlayers and shield layers S1 and S2.

Moreover, beveled edges and nonplanarity are avoided by maintainingplanar gap layer surfaces through use of the recessed portion 402 of theshield layer S1. To this end, the detrimental ramifications ofreflective notching and the swing curve effect are avoided.

FIG. 5 illustrates a plan cross-sectional view of the MR read head 400taken along line 5—5 shown in FIG. 4. As shown, the protruding portion404 of the shield layer S1 defines the recessed portion 402 in which thefirst gap layer G1 resides.

FIG. 6 illustrates a method 600 for fabricating the MR read head 400 ofFIGS. 4 and 5. Initially, in operation 602, the shield layer S1 isdeposited on a substrate. Thereafter, in operation 604, the recessedportion 402 is etched in an upper surface of the shield layer S1. Suchrecessed portion 402 of the shield layer S1 defines the protrudingportion 404 of the shield layer S1. The recessed portion 402 of theshield layer S1 is preferably of a predetermined depth that effectivelyprovides the desired amount of insulation.

Subsequently, the first gap layer G1 is deposited on top of the recessedportion 402 of the shield layer S1. Note operation 606. As an option, achemical-mechanical polishing process may be carried out on the uppersurfaces of the first gap layer G1 and the recessed portion 402 of theshield layer S1. Such chemical-mechanical polishing process serves toremove any residual nonplanarity around the protruding portion 404 ofthe shield layer S1.

In operation 608, the second gap layer G2 is deposited on top of thefirst gap layer G1 and the protruding portion 404 of the shield layerS1. Next, in operation 610, the MR sensor is positioned on top of thesecond gap layer G2 in vertical alignment with the protruding portion404 of the shield layer S1.

First and second lead layers are subsequently positioned on top of thesecond gap layer G2. Note operation 612. The first and second leadlayers are positioned such that they are connected to the MR sensor. Thethird gap layer G3 is then deposited on the second gap layer G2, the MRsensor, and the first and second lead layers, as indicated in operation614. While not shown, another shield layer S2 may be deposited on top ofthe third gap layer G3 in addition to any remaining layers that are wellknown to those of ordinary skill.

It should be understood that the order of operations in the method 600of fabrication may vary per the desires of the user. For example, theshield layer S1 and first gap layer G1 may both be deposited before thepatterning and etching processes are carried out to form the recessedportion 402 of the shield layer S1. Thereafter, the second gap layer G2and the MR sensor may be deposited. While this and other variations arepossible, the method 600 of fabrication is preferred since the MR sensoris deposited on a more pristine surface.

FIGS. 7A–7I illustrate the MR read head during the various stages offabrication in accordance with FIG. 6. As shown in FIG. 7A, the shieldlayer S1 is deposited in accordance with operation 602 of FIG. 6. FIG.7B illustrates the manner in which photoresist PR is deposited inpreparation for etching the recessed portion 402 of the shield layer S1in operation 604 of FIG. 6. FIG. 7C illustrates the results of theetching in accordance with operation 604 of FIG. 6.

FIG. 7D shows how the first gap layer G1 is deposited on top of therecessed portion 402 of the shield layer S1. Note operation 606 of FIG.6. FIG. 7E illustrates the manner in which the photoresist PR is removedafter operation 606 of FIG. 6. The second gap layer G2 is deposited ontop of the first gap layer G1 and the protruding portion 404 of theshield layer S1 in accordance with operation 608 of FIG. 6, as shown inFIG. 7F.

Next, the MR sensor is positioned on top of the second gap layer G2 invertical alignment with the protruding portion 404 of the shield layerS1 in accordance with operation 610 of FIG. 6. Note FIG. 7G. FIG. 7Galso shows additional photoresist PR that is deposited in anticipationof etching the MR sensor layer so that lead layers may be deposited overthe second gap layer G2 in accordance with operation 612 of FIG. 6. NoteFIG. 7H. As shown in such Figures, the MR sensor and lead layers areplanar as a result of being deposited on the planar first gap layer G1and planar second gap layer G2. This planarity enables the advantages ofthe present invention.

FIG. 7I shows the manner in which the third gap layer G3 is deposited inaccordance with operation 614 of FIG. 6. It should be noted that asecond shield layer S2 may subsequently be deposited as well.

To this end, the combined thickness of the gap layers is increased toreduce the chance of a short occurring between the lead layers andshield layers S1 and S2. Further, beveled edges and nonplanarity areavoided by maintaining planar gap layer surfaces. To this end, thedetrimental ramifications of reflective notching and the swing curveeffect are avoided.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of a preferred embodiment shouldnot be limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

1. A method for fabricating a magnetoresistive (MR) read headcomprising: depositing a shield layer; etching a recessed portion in anupper surface of the shield layer, the recessed portion of the shieldlayer defining a protruding portion of the shield layer; depositing afirst gap layer above the recessed portion of the shield layer;depositing a second gap layer above the first gap layer and theprotruding portion of the shield layer; positioning an MR sensor abovethe second gap layer; and positioning first and second lead layers abovethe second gap layer, the first and second lead layers being connectedto the MR sensor.
 2. The method as recited in claim 1, wherein the firstgap layer includes an upper surface substantially level with an uppersurface of the protruding portion of the shield layer.
 3. The method asrecited in claim 1, wherein an upper surface of the second gap layer isplanar.
 4. The method as recited in claim 1, further comprisingdepositing a third gap layer on top of the second gap layer, the MRsensor, wherein a combined thickness of the first gap layer, second gaplayer, and third gap layer is thinner adjacent to the MR sensor and theprotruding portion of the shield layer than the recessed portion of theshield layer.
 5. The method as recited in claim 1, wherein the recessedportion of the shield layer is etched utilizing ion milling.
 6. Themethod as recited in claim 1, wherein the recessed portion of the shieldlayer is etched utilizing reactive ion etching.
 7. The method as recitedin claim 1, wherein the recessed portion of the shield layer is etchedutilizing wet etching.
 8. The method as recited in claim 1, wherein thefirst gap layer and second gap layer are constructed from alumina. 9.The method as recited in claim 1, wherein the first gap layer and secondgap layer are constructed from aluminum oxide.
 10. The method as recitedin claim 1, wherein chemical-mechanical polishing is utilized to ensurethat an upper surface of the first gap layer is substantially level withan upper surface of the protruding portion of the shield layer.
 11. Themethod as recited in claim 1, wherein a size of the protruding portionof the shield layer is slightly larger than a size of the MR sensor. 12.The method as recited in claim 1, wherein the MR sensor is constructedfrom nickel iron.
 13. The method as recited in claim 1, wherein thefirst and second layers are constructed from copper.
 14. The method asrecited in claim 1, further comprising depositing a third gap layer ontop of the second gap layer, the MR sensor, wherein a combined thicknessof the first gap layer, second gap layer, and third gap layer is thinneradjacent to the MR sensor and the protruding portion of the shield layerthan the recessed portion of the shield layer in order to reduce thechance of a short occurring between the shield layer and the first andsecond lead layers.
 15. The method as recited in claim 1, wherein anupper surface of the second gap layer is planar to avoid detrimentalramifications of reflective notching.
 16. The method as recited in claim1, wherein an upper surface of the second gap layer is planar to avoiddetrimental ramifications of the swing curve effect.
 17. A method forfabricating a magnetoresistive (MR) read head, the read head comprising:a shield layer with a recessed portion and a protruding portion definedby the recessed portion, the recessed portion of the shield layer beingformed by an etching process; a first gap layer located on top of therecessed portion of the shield layer, the first gap layer including anupper surface substantially level with an upper surface of theprotruding portion of the shield layer; a second gap layer located ontop of the first gap layer and the protruding portion of the shieldlayer, an upper surface of the second gap layer being planar; an MRsensor located on top of the second gap layer in vertical alignment withthe protruding portion of the shield layer; and first and second leadlayers located on top of the second gap layer and connected to the MRsensor.
 18. The method as recited in claim 17, wherein the first gaplayer and second gap layer are constructed from alumina.
 19. The methodas recited in claim 17, wherein the first gap layer and second gap layerare constructed from aluminum oxide.
 20. The method as recited in claim17, wherein chemical-mechanical polishing is utilized to ensure that theupper surface of the first gap layer is substantially level with theupper surface of the protruding portion of the shield layer.
 21. Themethod as recited in claim 17, wherein a size of the protruding portionof the shield layer is slightly larger than a size of the MR sensor. 22.The method as recited in claim 17, wherein the MR sensor is constructedfrom nickel iron.
 23. The method as recited in claim 17, wherein thefirst and second lead layers are constructed from copper.
 24. The methodas recited in claim 17, further comprising depositing a third gap layeron top of the second gap layer, the MR sensor, wherein the combinedthickness of the first gap layer, second gap layer, and third gap layeris thinner adjacent to the MR sensor and the protruding portion of theshield layer than the recessed portion of the shield layer in order toreduce the chance of a short occurring between the shield layer and thefirst and second lead layers.
 25. The method as recited in claim 20,wherein the upper surface of the second gap layer is planar to avoiddetrimental ramifications of reflective notching.
 26. The method asrecited in claim 20, wherein the upper surface of the second gap layeris planar to avoid detrimental ramifications of the swing curve effect.